The issue seems so simple, it is surprising Florida's Department of Environmental Protection doesn't get it. Divers and ocean advocates are worried. Marine ecologist Brian Lapointe of Harbor Branch Oceanographic Institution, who specializes in nutrient pollution, is concerned. All fear Lake Worth's plans to dump 4 million gallons of nutrient-rich effluent into the ocean each day will harm Horseshoe Reef, one of South Florida's most beautiful and pristine reefs.

The effluent, left after a reverse osmosis system purifies drinking water, will spew from an old, 92-foot-deep outfall pipe, once used to dump sewage into the ocean. The 30-inch pipe, unused for years, will dump the briny waste near one of the area's best diving spots, where a diverse fish population thrives on a reef that includes a dome of living brain coral estimated to be more than 200 years old.

Lake Worth draws its water from the deep, brackish Floridan Aquifer, then forces it under high pressure through membranes to filter out salts and impurities. DEP officials say they don't think the concentrate of ammonia, phosphorus and nitrogen, all "fertilizers" for algae, will fuel an algae bloom on or near the reef. The agency has issued Lake Worth a draft permit, allowing the city to use the sewage pipe if it tests where the effluent goes when it leaves the pipe. The DEP has no numeric standards for pollutants discharged into the ocean, only a requirement that the city can't have a discharge "which will cause an imbalance" in ocean plants or animals.

Trouble is, as many reef defenders have pointed out, the reef could be destroyed before officials perform enough tests to show the discharge is destroying the reef. The brine left over from purifying water isn't a "natural" substance to discharge into the ocean, said Jim Egan, executive director of the Marine Resources Council. Pumping the briny waste back underground, where at least the waste resembles the content of the water from which it was removed, makes more sense than dumping it in the ocean. Island nations that use reverse osmosis to make ocean water drinkable, he said, discharge the effluent back to the ocean without much impact. But ocean systems are more expensive.

DEP will rely on the city's tests to show Lake Worth's effluent won't harm the reef. "If we get an unanticipated result," said Janet Llewellyn, Division of Water Resources Management director, "we could take another look." But that could be too late.

A better plan: Make Lake Worth dispose of the waste underground, or at the very least, move the pipe far from the reef. Growth and water scarcity, even when the drought ends, will put more straws into the deep aquifer, already under pressure, that Lake Worth is using. Florida soon must plan to use its most abundant untapped water source: the Atlantic.